Generally, an adhesive totally refers to a substance used for combining the same kinds of objects or different kinds of objects, and refers to a high molecular substance which is liquefied at the beginning and solidified as time goes by to tightly ‘adhere’ to an object and is not destroyed in itself. In this case, the ‘adhesion’ of the adhesive is different from a ‘join’ in that a wetting follows the adhesion, and the wetting is a phenomenon caused by mutual similarity between the adhesive and the object. If a liquefied adhesive ‘contacts’ with an object, it penetrates uniformly into the object by the ‘wetting’ to ‘combine’ with the object and be solidified according to a dynamic and chemical adhesive strength of factors generating an adhesive intensity, for example, an anchor, a zipper, capillary and the like. Once the adhesive is solidified, it ‘keeps’ the adhesive state tightly regardless of external factors such as temperature, humidity, pressure or the like. Therefore, a good adhesive should be outstanding in all characteristics of the ‘contact’ the ‘wetting’ the ‘combine’ and the ‘keep’. Currently, mainly employed adhesives are largely classified into an inorganic adhesive and an organic adhesive, which may be classified in detail depending on a major ingredient thereof, as shown in the following Table 1.
TABLE 1InorganicCement type, Sodium Silicates (water glass) type,AdhesiveCeramics, othersOrganicSyntheticThermosettingUrea base, Melanin base,AdhesiveresinsPhenol base, UnsaturatedbasePolyester base, Epoxybase, Resorcinol baseThermoplasticVinyl Acetate base, PolyvinylAlcohol base, Vinyl Chloridebase, Polyvinyl Acetal base,Acryl base, Saturated Polyesterbase, Polyamide base,Polyethylene baseRubber baseButadiene Rubber base, Nitrile(Styrene type)Rubber base, Butyl Rubberbase, Silicone Rubber base,ChloropreneRubberMixture baseVinyl based Phenol-Chloroprenebase(Phenol type)baseEpoxyPolyamide base,Nitrile Rubber-Epoxy baseNaturalDextrin baseStarch, DextrinbaseProtein baseGlue, CaseinResin basePine resin, ShellacRubber baseLatex, MucilageAsphalt paper
On the other hand, recently, concern about a comfortable residence environment increases gradually as an environmental pollution becomes serious, and thus an effort to reduce damages, for example, sick house syndrome, headache, atopic dermatitis, asthma and the like induced by poisonous chemicals such as formaldehyde or the like. Herein, the sick house syndrome means a phenomenon induced by volatile organic compounds (“VOCs”) such as formaldehyde, benzene, toluene, xylene, ethylbenzene, acetaldehyde, dichlorobenzene, styrene, etc., and the cause thereof can be found in adhesives, construction materials and the like containing such chemicals. Thus, recently, although a demand for so-called ‘Natural adhesive’ which eliminates addition and use of the volatile organic compounds, if possible, increases, if the use of the volatile organic compounds is completely eliminated from the whole procedures of fabrication and production, the natural adhesive has a disadvantage that preservation thereof deteriorates to be easily contaminated by germs and the like. For this reason, a small amount of preservative ingredient such as formaldehyde is contained in most of natural adhesives available from the market. Moreover, the volatile organic compounds are used in process of fabrication and preservation of a resin, a solvent, a catalyst, a hardener, an additive and the like which are ingredients of the natural adhesive, without any restrictions.
As a result, the volatile organic compounds are evaporated in process of dry and hardening of the natural adhesive to generate a carcinogen as well as to induce ailment damages such as a sick house syndrome, for example, headache, atopic dermatitis, asthma and the like, and further to induce destruction of an ozone layer and a global warming due to photochemical smog.